1. Technical Field
This invention relates to vegetable extracts, more specifically extracts of coffee and processes for producing such products. Coffee extract in the form of a high solids melt is mixed with oil, colloidal ground coffee or other edible cellulosic material to form a discontinuous phase in the final coffee which improves solubility. The melt is gasified, forced through an orifice and cooled to form a controlled light density coffee glass which when granulated and sized has the appearance of roasted and ground coffee, freeze-dried coffee or other useful appearances depending on the degree of gasification. The melt may be aromatized prior to formation of the desired shape and the aroma may in whole or part be contained in the added coffee oil or matrix solubilizing material. The product exiting the die may be stretched to cool and control its final form. An object of this invention is to provide economical processes for shaping and preparing shelf-stable coffee products which have not suffered from heat damage and yet may be quickly reconstituted in hot water to yield coffee of excellent flavor and aroma. The process is particularly suitable for producing aromatized gasified coffee of controlled density and color which can be sized and dried to a stable condition without need for extensive freeze or spray drying. Such gasified soluble coffee glass can then be further treated, as by agglomeration, to form novel appearing products.
The invention is particularly useful to produce products of flavor, solubility and appearance equal to freeze-dried coffee without the need to freeze dry.
2. Prior Art
The present invention is concerned with the manufacture of vegetable extracts and, particularly, instant coffee. The manufacture of instant coffee involves extracting roasted and ground coffee beans with water under conditions of high temperature and pressure to form extracts which are dried with or without aromas added by known means, such as spray drying, freeze drying or the like.
In an early effort to avoid drying of such coffee extracts by Eskew, U.S. Pat. No. 2,989,717, issued Mar. 22, 1960, a fifty-fifty mixture of concentrated coffee extract and an invert sugar solution were concentrated in a thin film evaporator to form a product having four percent or less water which was pumped out of the evaporator and formed on chilling rolls into small flakes which were easily broken into a coarse product before packaging. In this process, the product temperatures exiting the evaporator ranged from 220.degree. F. to 290.degree. F. and the products produced had moisture contents of about 1 to 4% and were hygroscopic by reason of the addition of large amounts of invert sugars. This type of processing was also applied by Turkot, et al., U.S. Pat. No. 2,908,630, issued Sept. 29, 1959. While the process of Eskew and Turkot, et al. produced coffee products without the need to spray dry, a filler was employed which is not suitable in today's market. Furthermore, special packaging would be required to reduce the chance of moisture contamination which would be disastrous because of the hygroscopicity of the coffee product produced.
In another attempt, Earle Jr., et. al., U.S. Pat. No. 3,419,399 patented Dec. 31, 1968, prepared soluble coffee doughs having a moisture content of 9.5 to 12.5% at a temperature below 140.degree. F. and then dried the dough to 1-4%. This material was very sticky and difficult to process.
Another attempt to produce dehydrated vegetable extracts is disclosed by Risler, et. al., U.S. Pat. No. 4,154,864, issued May 15, 1979. Risler, et. al. formed a paste or powder which is extruded into a subatmospheric pressure chamber to puff the coffee product. For example, freeze-dried instant coffee powder, having a moisture content of 2.5%, is extruded into a chamber at 80 mb and cut to form grains about the size of a pea which dissolve in cold water. When compared to these grains extruded into atmospheric pressure in Example 5 of that patent, the products with cellular internal structure are far more soluble.
In U.S. Pat. No. 3,625,704 to Andre, et al., issued Dec. 7, 1971, dense flakes of instant coffee are prepared and aromatized from roll-milled instant coffee.
In the field of flavor fixation, particularly of essential oils, a number of patents have issued which deal with forming a carbohydrate glass to protect the flavor. The U.S. Pat. No. 3,041,180, issued to Swisher, discloses a method for fixing flavorants in an extruded carbohydrate substrate. The product of the Swisher invention is obtained by emulsifying an essentially water-insoluble essential oil with a molten mixture of glycerol and corn syrup solids as the continuous phase, extruding the emulsified mass in the form of filaments into a cold fluid, preferably an organic solvent for the essential oil which is a nonsolvent for the corn syrup solids; followed by impact breaking of the solidified filaments into small particles of usable form and then holding the particles in the solvent, preferably for an extended period, to remove essential oil from the surfaces of the particles together with a substantial portion of the residual moisture contained on and in the particles. This methodology is conducted in excess of 130.degree. C.
U.S. Pat. No. 3,704,137 to Beck discloses a method for preparing an essential oil composition. His method involves the cooking of an aqueous solution of sucrose and hydrolyzed cereal solids until it is at a boiling point of about 122.degree. C., and the water level reaches a desired minimum. At this point the heating is stopped, the mixture is agitated, and an emulsifier is added. The emulsifier is necessary in order for a homogeneous solution to form. While the solution is cooling, the essential oil and an antioxidant are added, and are intimately mixed. The final mix is forced through an extruder under air pressure. At this point, about 0.5% by weight of the final composition of an anticaking agent is added to prevent the particles from sticking.
U.S. Pat. No. 4,004,039 to Shoaf, et al. discloses a process for the encapsulation of "Aspartame" in any number of matrix forming materials. The product is formed by creating a hot melt which, upon cooling, is capable of forming a relatively amorphous matrix within which the sweetener is discretely dispersed.
EPO published patent application 0158460 to Pickup, et al., teaches a method for fixing volatile flavorants in a food-approved substrate, and, more particularly, to a low-temperature methodology for fixing volatile flavorants in an extruded "carbohydrate-glass" substrate. Volatiles or essential oils are dry blended with 10-30% low molecular weight carbohydrate food acid or the like and at least 70% of a high molecular weight polymeric carbohydrate which contains at least 95% material above 1000 molecular weight. The dry mixture is extruded to form on cooling a hard glass-like substance.
While these methods have enabled workers in the art to produce useful food products, they have not provided a means for producing aromatized coffee glass which is prepared from 100% coffee derived material.